Considering this, if it is proved that the agent, Cilostazol, could decrease the risk of occurrence of stoke, along with no significant increase in the risk of occurrence of hemorrhagic side effects, by selecting a patent group with a high risk of cerebral hemorrhage, the agent (Cilostazol) may be recognized as an unique antiplatelet agent applicable to old-aged patient with cerebral infarction who have a certain risk of cerebral hemorrhage.